Loss of the spectraplakin gene Short stop induces a DNA damage response in Drosophila epithelia

Sci Rep. 2020 Nov 19;10(1):20165. doi: 10.1038/s41598-020-77159-y.

Abstract

Epithelia are an eminent tissue type and a common driver of tumorigenesis, requiring continual precision in cell division to maintain tissue structure and genome integrity. Mitotic defects often trigger apoptosis, impairing cell viability as a tradeoff for tumor suppression. Identifying conditions that lead to cell death and understanding the mechanisms behind this response are therefore of considerable importance. Here we investigated how epithelia of the Drosophila wing disc respond to loss of Short stop (Shot), a cytoskeletal crosslinking spectraplakin protein that we previously found to control mitotic spindle assembly and chromosome dynamics. In contrast to other known spindle-regulating genes, Shot knockdown induces apoptosis in the absence of Jun kinase (JNK) activation, but instead leads to elevated levels of active p38 kinase. Shot loss leads to double-strand break (DSB) DNA damage, and the apoptotic response is exacerbated by concomitant loss of p53. DSB accumulation is increased by suppression of the spindle assembly checkpoint, suggesting this effect results from chromosome damage during error-prone mitoses. Consistent with DSB induction, we found that the DNA damage and stress response genes, Growth arrest and DNA damage (GADD45) and Apoptosis signal-regulating kinase 1 (Ask1), are transcriptionally upregulated as part of the shot-induced apoptotic response. Finally, co-depletion of Shot and GADD45 induced significantly higher rates of chromosome segregation errors in cultured cells and suppressed shot-induced mitotic arrest. Our results demonstrate that epithelia are capable of mounting molecularly distinct responses to loss of different spindle-associated genes and underscore the importance of proper cytoskeletal organization in tissue homeostasis.

Publication types

  • Research Support, N.I.H., Extramural
  • Video-Audio Media

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Apoptosis / genetics
  • Cells, Cultured
  • Chromosome Segregation
  • DNA Breaks, Double-Stranded
  • DNA Damage / physiology*
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / cytology
  • Drosophila melanogaster / genetics*
  • Epithelial Cells / physiology
  • Epithelium
  • GADD45 Proteins
  • Intracellular Signaling Peptides and Proteins / genetics
  • Larva / genetics
  • MAP Kinase Kinase Kinases / genetics
  • MAP Kinase Kinase Kinases / metabolism
  • Microfilament Proteins / genetics*
  • Mitosis
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • Wings, Animal / physiology*
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Drosophila Proteins
  • Intracellular Signaling Peptides and Proteins
  • Microfilament Proteins
  • Tumor Suppressor Protein p53
  • p53 protein, Drosophila
  • shot protein, Drosophila
  • p38 Mitogen-Activated Protein Kinases
  • ASK1 protein, Drosophila
  • MAP Kinase Kinase Kinases